Adherence to Rescreening for Colorectal Cancer with Faecal Occult Blood

Testing

Amy Claire Duncan

Bachelor of Health Science (Honours)

Thesis submitted in fulfilment of the requirements for the Degree of Doctor of

Philosophy

School of Psychology

The University of Adelaide

June 2012

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Contents List of Tables and Figures ........................................................................................................... vii

Abstract .............................................................................................................................................. ix

Declaration ...................................................................................................................................... xii

Acknowledgements .................................................................................................................... xiii

List of Abbreviations .................................................................................................................... xv

Chapter One- Introduction ........................................................................................................... 1

Preamble ........................................................................................................................................................ 1

Colorectal Cancer Epidemiology........................................................................................................... 1

Screening for Colorectal Cancer............................................................................................................ 3

Definition of screening ........................................................................................................................ 3

Screening tests for Colorectal Cancer ............................................................................................ 4

Colorectal Cancer Rescreening ........................................................................................................... 11

Definition ............................................................................................................................................... 11

Rescreening Rates .............................................................................................................................. 12

Methodological Difficulties in Rescreening Research ............................................................... 18

Assessing outcomes in CRC screening research. .................................................................... 18

Defining outcomes in CRC rescreening research. .................................................................. 22

Frameworks for describing and analysing CRC rescreening behaviour. ...................... 23

Factors associated with Rescreening............................................................................................... 29

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Demographic predictors of rescreening .................................................................................... 32

Background predictors of CRC rescreening ............................................................................. 33

Prior participation in FOBT screening ............................................................................................ 34

Behavioural predictors of rescreening. ...................................................................................... 36

Summary and Suggestions for Future Research ......................................................................... 36

Chapter Two- Thesis Design ...................................................................................................... 38

Preamble ..................................................................................................................................................... 38

Social Cognitive Associations with CRC Screening ..................................................................... 39

Barriers and benefits. ........................................................................................................................ 39

Perceived severity and susceptibility. ........................................................................................ 41

Perceived behavioural control. ..................................................................................................... 42

Social influence. ................................................................................................................................... 44

Implementation intentions. ............................................................................................................ 46

Thesis Aims ................................................................................................................................................ 47

Methodology .............................................................................................................................................. 48

Thesis Design ............................................................................................................................................ 50

Summary ..................................................................................................................................................... 54

Chapter Three, Paper One- Qualitative Exploration of Participants Experiences

Screening and Rescreening with Faecal Occult Blood Tests for Colorectal Cancer.

.............................................................................................................................................................. 55

Preface ......................................................................................................................................................... 55

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Abstract ....................................................................................................................................................... 59

Background ................................................................................................................................................ 61

Method ......................................................................................................................................................... 62

Selection criteria. ................................................................................................................................ 62

Recruitment. ......................................................................................................................................... 63

Interviews. ............................................................................................................................................. 64

Analysis. .................................................................................................................................................. 64

Results ......................................................................................................................................................... 65

Participants. .......................................................................................................................................... 65

Factors associated with participation in initial and repeated screening. ..................... 65

Discussion................................................................................................................................................... 74

Chapter Four, Paper Two- Using the Transtheoretical Model of Behaviour Change

to Describe Readiness to Rescreen for Colorectal Cancer with Faecal Occult Blood

Testing ............................................................................................................................................... 79

Preface ......................................................................................................................................................... 80

Abstract ....................................................................................................................................................... 83

Background ................................................................................................................................................ 85

Methods ....................................................................................................................................................... 87

Rescreening questionnaire. ............................................................................................................ 88

Background variables. ...................................................................................................................... 92

Analyses ................................................................................................................................................. 93

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Exclusions. ............................................................................................................................................. 93

Results ......................................................................................................................................................... 94

Questionnaire respondents. ........................................................................................................... 94

Distribution across the stages of the TTM. ............................................................................... 95

Univariate analyses. ........................................................................................................................... 95

Multivariate analyses. ....................................................................................................................... 98

Discussion................................................................................................................................................. 100

Chapter Five, Paper Three- Adherence to Faecal Occult Blood Testing Over

Multiple Screening Rounds: Behavioural Predictors of Participation in Three

Consecutive Screening Opportunities. ................................................................................ 105

Preface ....................................................................................................................................................... 105

Abstract ..................................................................................................................................................... 109

Background .............................................................................................................................................. 111

Methods ..................................................................................................................................................... 115

Study population. .............................................................................................................................. 115

Study design. ....................................................................................................................................... 115

Materials............................................................................................................................................... 116

Study outcome. .................................................................................................................................. 118

Analyses. ............................................................................................................................................... 120

Exclusions. ........................................................................................................................................... 121

Results ....................................................................................................................................................... 122

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Participants. ........................................................................................................................................ 122

Rescreening adherence. ................................................................................................................. 122

Univariate differences between consistent reparticipation and non-adherence. ... 123

Multivariate predictors of non-adherence. ............................................................................. 126

Satisfaction with prior FOBT participation. ........................................................................... 129

Discussion................................................................................................................................................. 132

Conclusions .............................................................................................................................................. 138

Chapter Six- Discussion ............................................................................................................ 139

Preface ....................................................................................................................................................... 139

Rescreening Adherence in Australia .............................................................................................. 139

Behavioural Associations with Rescreening ............................................................................... 142

Social cognitive variables. ............................................................................................................. 143

Satisfaction with prior screening experiences. ..................................................................... 146

Demographic and Background Variables ..................................................................................... 147

Suggestions for Future Research ..................................................................................................... 147

Implications for Screening Practice and Intervention ............................................................ 154

Strengths and Limitations .................................................................................................................. 157

Sampling ............................................................................................................................................... 158

Thesis Design...................................................................................................................................... 159

Questionnaire Design ...................................................................................................................... 160

Concluding Comments .................................................................................................................... 161

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Appendices ................................................................................................................................... 162

Appendix A: Rescreening Questionnaire ...................................................................................... 162

Appendix B: Prepublication Version of Paper Two ...................................................................... 187

Appendix C: Advance Notification Letter ..................................................................................... 213

Appendix D: BHS Annual Screening Invitation Letter ............................................................. 214

Appendix E: Bowel Cancer Screening Information Sheet ...................................................... 215

References .................................................................................................................................... 217

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List of Tables and Figures

Table 1 Rates of reparticipation in two rounds of screening reported in the literature.14

Table 2 Rates of complete/adequate compliance with more than two screening rounds

using FOBT......................................................................................................................... .................................17

Table 3 Stage of Readiness definitions as they apply to mammography screening defined

by Rakowski et al (1996)..............................................................................................................................25

Table 4 Multivariate demographic associations with rescreening adherence and study

descriptions............................................................................................................................. ............................31

Table 5 Aims, sampling frame, sample size and outcome measures for the three thesis

paper............................................................................................................................. .........................................53

Table 6 Factors associated with participation in initial and repeat screening......................66

Table 7 Social cognitive measures used in the rescreening questionnaire.............................91

Table 8 Significant univariate differences between maintenance and remaining

categories for social cognitive variables.................................................................................................96

Table 9 Significant univariate differences between maintenance and remaining

categories for demographic and background variables..................................................................97

Table 10 Multivariate analyses of factors associated with the action, inconsistent and

relapse stages relative to maintenance...................................................................................................99

Table 11 FOBT screening patterns and behaviours defined for three screening

rounds.................................................................................................................................................................120

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Table 12 Proportion of study participants in each adherence category upon study

completion (i.e., at year 3).........................................................................................................................123

Table 13 Significant social cognitive differences between consistent reparticipation and

each non-adherent category ....................................................................................................................124

Table 14 Demographic and background differences between consistent reparticipation

and categories of non-adherence...........................................................................................................125

Table 15 Multivariate predictors of non-adherence relative to consistent

reparticipation...............................................................................................................................................128

Table 16 Multivariate predictors of non-adherence relative to consistent reparticipation

including a measure of prior satisfaction with FOBT....................................................................131

Table 17 Rescreening outcomes and population distribution..................................................142

Figure 1 NHMRC project overview and thesis subpopulations...................................................52

Figure 2 Process of determining eligibility for analyses..............................................................121

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Abstract

This thesis aimed to describe and predict adherence to Faecal Occult Blood Test

(FOBT) rescreening recommendations in South Australia. Specifically this thesis aimed

to determine the relevance of social cognitive variables for explaining variations in

rescreening adherence. FOBT screening for colorectal cancer (CRC) is recommended

every one to two years for those over the age of 50; reductions in incidence and

mortality from CRC are dependent on continued compliance with these guidelines.

Whilst there has been substantial research on factors associated with initial screening

participation, there has been very little research conducted on how to encourage

rescreening adherence (i.e., continued participation in annual or biennial screening

offers). The few studies that have examined predictors of rescreening have, to date,

limited their exploration to demographic and health systems factors. This thesis aims to

determine the relevance of the inclusion of behavioural factors previously associated

with initial screening (i.e., social cognitive variables) for explaining rescreening and also

to explore potential new predictors of rescreening not previously examined in CRC

rescreening research.

The thesis used a sequential, mixed-methods research design to address the aims.

Three separate studies, one qualitative and two quantitative, were used to explore

predictors of adherence to FOBT rescreening. The three studies are presented as three

separate papers in the thesis. Study one used 17 semi-structured interviews to explore

rescreening participants’ past experience with FOB testing. Exploratory thematic

analysis was used to determine factors relevant for inclusion in a subsequent

questionnaire. The questionnaire was then administered to 4000 potential participants

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within the target age range for FOBT screening (50-75 years) in South Australia. Study

two analysed questionnaire data to determine associations with stage of readiness

(intention) for rescreening. Following survey completion, respondents (survey response

rate of 49%) were provided with three annual offers to screen with FOBT. Data collected

during the questionnaire phase were used to identify variables predictive of rescreening

adherence. Univariate and multivariate modelling were used to determine associations

with intention and adherence.

Results of study one revealed that many of the factors previously associated with

initial screening (e.g., perceived barriers, benefits and social influence) were associated

with rescreening. However, specific barriers, for example, maintaining a screening

routine, were identified for rescreening. In addition previous screening experience

appeared to influence attitudes toward future participation i.e., improved participants

self-efficacy with regard to future participation and reinforced the perceived benefits of

participation.

Study two found that almost 30% of prior screeners were non-adherent with

rescreening. Social cognitive (self-efficacy, perceived barriers and benefits, social

influences, implementation intentions) and demographic/background variables (age,

knowledge, and health insurance coverage) were associated with rescreening intention.

Conversely, in study three, only few social cognitive variables (perceived barriers, self-

efficacy and response efficacy) were marginally associated with screening adherence

across three rounds of screening. The demographic variables gender, insurance and

marital status better differentiated patterns of adherence. When a measure of

satisfaction with prior FOBT screening was added to the multivariate models in study

three, none of the social cognitive variables significantly predicted adherence.

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Satisfaction with prior screening substantially increased rescreening intention and

adherence by 13% and 42% in studies two and three respectively.

Results of the thesis indicate that although social cognitive variables

differentiated intentions to rescreen, when demographic variables and satisfaction with

prior screening were held constant, social cognitive variables did little to predict

rescreening adherence. Satisfaction with prior screening was an important predictor of

both rescreening intention and adherence. Exploration of the factors contributing to

satisfaction with screening may provide an important opportunity to modify and

improve screening services to encourage rescreening. Several demographic variables

were also found to have a substantial impact on intention and adherence. An

investigation of how these demographic and background factors interact with social

cognitive variables may allow for greater tailoring of messages to encourage

rescreening.

xii

Declaration

This work contains no material which has been accepted for the award of any

other degree or diploma in any university or other tertiary institution to Amy Duncan

and, to the best of my knowledge and belief, contains no material previously published

or written by another person, except where due reference has been made in the text.

I give consent to this copy of my thesis when deposited in the University Library,

being made available for loan and photocopying, subject to the provisions of the

Copyright Act 1968.

The author acknowledges that copyright of published works contained within

this thesis (as listed below) resides with the copyright holder(s) of those works.

I also give permission for the digital version of my thesis to be made available on

the web, via the University’s digital research repository, the Library catalogue, the

Australasian Digital Theses Program (ADTP) and also through web search engines,

unless permission has been granted by the University to restrict access for a period of

time.

Chapter four, paper two:

Duncan, A., Turnbull, D., Gregory, T., Cole, S., Young, G., Flight, I., et al. (2012). Using the Transtheoretical Model of Behaviour Change to describe readiness to rescreen for colorectal cancer with faecal occult blood testing. Health Promotion Journal of Australia, 23, 122-128.

Amy Claire Duncan

Signed: date:

xiii

Acknowledgements

There are many people I would like to thank for their assistance, support and

guidance over the past few years.

To my supervisors Deborah Turnbull and Carlene Wilson thank you so much for

your feedback, guidance and advice during this time, you have been invaluable. Thank

you for your prompt feedback on the countless drafts that have come your way over the

years and for your encouragement and patience especially in the final stages. To Deb,

thank you for always helping me to see the bigger picture and for allowing me to

interrupt you countless times for impromptu meetings. To Carlene, thank you for always

helping me to see the practical implications of our research and for your keen editorial

eye. Also, a big thank you to you both for allowing me to travel during my candidature

and being flexible with thesis timelines to accommodate this.

To the entire Adelaide Colorectal Cancer Collaborative and associated grant

employees both past and present, none of this would have been possible without you. To

the grant Chief Investigators (Graeme Young, Stephen Cole, Ingrid Flight, Deborah

Turnbull, Carlene Wilson and Adrian Esterman) thank you for giving me the opportunity

to be involved in this research and for providing ongoing advice, assistance and

guidance throughout the research program. Ian Zajac and Tess Gregory I am extremely

grateful for your assistance with data analyses and interpretation. Thank you to the

entire team at RGH you have been a pleasure to work with, a special thanks to Jo

Osborne for managing a very complex screening program and assisting with data entry

and classification of screening outcomes. Thank you to Julie Syrette at CSIRO for

creating a fool proof data entry system and Elizabeth Hart for verifying data entry.

xiv

To all my uni friends, in particular Ang, Jo, Suzie, Katie, Chrisi and Victoria thank

you for everything! Thanks for the many drinks, coffee, dinner, lunch and shopping

dates. In particular a big thank you for letting me talk about formatting, statistics and

other thesis related topics at these catch ups especially when your theses had become

things of the past! Your support and advice, especially during these final stages, was

extremely valuable. I am really glad to have made such a great group of friends during

my candidature, you made thesis time fun! To my office mates in 245 and 721, thank you

for the much needed chats (often shouted through a dividing wall!) and for providing

some much needed company on those long days spent underground. Thank you to

everyone in the School of Psychology, past and present, for creating a great environment

to work in.

To all my friends and family thank you for your ongoing support and always

believing in me. Mum and Dad thank you for being eternally optimistic, proud and

supportive. Helen, thank you for your continued enthusiasm for all things thesis related,

your interest in my topic, progress and findings never ceased to amaze me! Thanks to

Lib for being my travel buddy. To all the girls, you are awesome, thanks for the weekend

winery distractions, holidays and wedding fun!

Finally a big thank you to Mitch for just being amazing in general. Thank you for

enduring my many mood swings and moments of self doubt. Thank you for dropping

everything to come and explore Canada with me. Thank you for letting me discuss minor

details of my thesis at great length without complaint, and thank you for your

unwavering support and belief that I would finish this.

xv

List of Abbreviations

BHS- Bowel Health Service

CRC- colorectal cancer

FOBT- faecal occult blood test

FS- flexible sigmoidoscopy

HBM- Health Belief Model

MHLC- Multidimensional Health Locus of Control

NBCSP- national bowel cancer screening program (Australian)

NBCSPP- national bowel cancer screening pilot program (Australian)

NHMRC- National Health and Medical Research Council

RCT- randomised controlled trial

SCT- Social Cognitive Theory

TPB- Theory of Planned Behaviour

TTM- Transtheoretical Model of Behaviour change

PMT- Protection Motivation Theory